Actuator with flexible cylinders

ABSTRACT

An actuator comprises a plurality of flexible cylinders arranged adjacent to one another. The inside of each of the flexible cylinder is divided into a plurality of pressure chambers with partition walls that extend axially inside the flexible cylinder. The actuator has a pressure adjuster for adjusting pressures in the respective pressure chambers of the flexible cylinders so that the flexible cylinders may operate at individual degrees of freedom in achieving cooperative motions.

This application is a continuation, of application Ser. No. 07/945,267,filed Sep. 15, 1992, now abandoned, which is a continuation, ofapplication Ser. No. 07/631,812, filed Dec. 20, 1990, U.S. Pat. No.5,156,081.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an actuator employing flexiblecylinders that elastically deform in response to applied fluidpressures, and particularly to an actuator that can easily handle a softor fragile object or an object having many curved faces.

2. Description of the Prior Art

Robots are widely used in recent years, and there are requirements todevelop a robot hand that can easily handle a soft thing such as a fruitand a small animal, a fragile thing such as a glass cup, or a thinghaving many curved faces such as a ball and a cone. It is also requiredto transfer an object by fingertips of the robot hand.

Most of conventional robot hands have two fingers, and therefore, areincapable of handling an object which is soft, or fragile, or providedwith many curved faces. It is also difficult for the conventional robothands to transfer an object because it needs a very complicated controlalgorithm.

Multifinger robot hands now under study involve complicated mechanismsand control algorithms to hardly meet the above requirements.

In this way, the conventional robot hands involve complicated controlalgorithms and cannot sufficiently handle soft or fragile objects.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an actuator that caneasily hold an object that is soft, fragile, or provided with manycurved faces, and effectively handle the object.

In order to accomplish the object, an apparatus according to the presentinvention comprises a plurality of flexible cylinders arranged adjacentto one another. The inside of each of the flexible cylinder is dividedinto a plurality of pressure chambers with partition wails that extendaxially inside the flexible cylinder. The actuator has pressureadjusting means for adjusting pressures in the respective pressurechambers of the flexible cylinders so that the flexible cylinders mayoperate at individual degrees of freedom in achieving cooperativemotions.

According to one aspect of the present invention, at least a peripheralwall of each of the flexible cylinders has anisotropic elasticity sothat, by adjusting pressures in the respective pressure chambers, theflexible cylinders may separately act. Base portions of the flexiblecylinders are fixed to a common base. Since the peripheral walls of theflexible cylinders have anisotropic elasticity, the flexible cylinderselastically deform when the pressure chambers are filled withpressurized fluids. Namely, the flexible cylinders axially extend orcontract (with turning motions around their respective axial centers, ifthe anisotropic elasticity allows), or curve in optional directions. Theflexible cylinders cooperatively move to hold and handle an object.

These and other objects, features and advantages of the presentinvention will be more apparent from the following detailed descriptionof preferred embodiments in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a general view showing an actuator according to a firstembodiment of the present invention;

FIGS. 2a and 2b are plan views showing the actuator of FIG. 1;

FIG. 3 is a sectional view taken along a line III--III of FIG. 2a;

FIG. 4 is a perspective view showing the exterior of an flexiblecylinder of the actuator of FIG. 1;

FIG. 5 is an exploded perspective view showing the flexible cylinder;

FIGS. 6a to 8b are views explaining a first operation of the actuator;

FIGS. 9a to 9c are views explaining a second operation of the actuator;

FIGS. 10 to 13b are views explaining motions of the actuator in handlingan object M;

FIGS. 14 and 15 are views showing modifications of the first embodiment,having many flexible cylinders;

FIGS. 16 and 17 are views explaining a third operation of the actuatorof the first embodiment;

FIGS. 18a and 18b are views explaining another operation involving aturning motion, of the first embodiment;

FIGS. 19 to 22 are views showing second, third, and fourth embodimentsof the present invention; and

FIGS. 23 to 25 are views showing modifications of the flexible cylinder.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIGS. 1 to 3 are views showing an actuator according to the firstembodiment of the present invention, in which FIG. 1 shows anarrangement of the actuator (a robot hand), FIGS. 2a and 2b are planviews of the actuator, and FIG. 3 is a sectional view taken along a lineIII--III of FIG. 2a.

In the figures, numeral 1 denotes the actuator which comprises aplurality (four in this embodiment) of flexible cylinders 3, 5, 7, and9. Base portions 3a, 5a, 7a, and 9a of the flexible cylinders are heldbetween a base 11 of the actuator 1 and support members 13, 15, 17, and19, and fastened with screws 20. The base portion is mounted in adepression (1003, 1005, 1007, 1009) in at least one of the base and arespective one of the support members. The flexible cylinders areequidistantly arranged along a circle 21 on the base 11. Center axes 3b,5b, 7b, and 9b of the flexible cylinders are in parallel with oneanother.

The flexible cylinders 3, 5, 7, and 9 have pressure chambers 301, 302,303; 501, 502, 503; 701, 702, 703; and 901, 902, 903 as shown in FIG.2b.

Among the flexible cylinders which are identically constituted, theflexible cylinder 3 will be explained with reference to FIGS. 4 and 5.

A peripheral wall of the flexible cylinder 3 comprises a tubular elasticbody 23 having anisotropic elasticity. The tubular elastic body 23having anisotropic elasticity. The tubular elastic body 23 is made of,for example, circumferentially wound fibers. Namely, the tubular elasticbody 23 includes fiber wound around the axis spirally with fineinter-fiber spaces, and a silicone rubber coated over the fiber. Byforming the tubular elastic body 23 from an anisotropic materialcombined of the fiber and the rubber, a direction small in modulus oflongitudinal elasticity is substantially aligned with the axialdirection of the tubular elastic body 23, and the tubular elastic body23 is easily extendible in the axial direction. But in a directionperpendicular to the axial direction, the tubular elastic body 23 ishardly extendible because it is large in modulus of elasticity due tothe fiber. The tubular elastic body 23 has a plurality (three in thisembodiment) of elastic partition walls 27, 29, and 31 that extend alonga center axis 25 of the elastic tubular body 23 to define a plurality(three in this embodiment) of pressure chambers 301,302, and 303 insidethe elastic tubular body 23.

One ends of the pressure chambers are closed with lids 33, 35, and 37. Around tip member 39 is adhered to end faces of the lids. The other endsof the pressure chambers are closed with lids 47, 49, and 51, which aremade of relatively hard elastic material and have through holes 41, 43,and 45, respectively. As the material of the lids 47, 49, and 51, it ispossible to employ the material same as that of the elastic tubular body23, a metal material, or a plastic material. A portion of the elastictubular body 23 which is provided with the lid become each of the baseportions 3a-9a. The base portion has a thickness greater than thethickness of the tubular elastic body.

Tubes 53 pass through the through holes and slightly protrude into thepressure chambers 301, 302, and 303. These tubes 53 guide a fluid suchas air from a fluid source 54 into the pressure chambers as shown inFIG. 1. Fluid pressures in the pressure chambers are separatelyadjustable with valves 57 that control flow rates of the fluid from thefluid source 54 and with a computer 55 that controls the valves 57, sothat the tubular elastic body 23 may curve and deform through elasticexpansion/contraction along the center axis 25, or turn around thecenter axis 25. As the valve 57, it is possible to employ a pressurecontrol valve for example.

The other flexible cylinders 5, 7, and 9 have the same arrangement asthat of the flexible cylinder 3. The flexible cylinder 5 has pressurechambers 501, 502, and 503, the flexible cylinder 7 has pressurechambers 701, 702, and 703, and the flexible cylinder 9 has pressurechambers 901, 902, and 903. Ends of tubes 53 protrude into thesepressure chambers, and the other ends of the tubes 53 are connected tothe fluid source 54 through valves 57.

The tubular elastic body 23, lids 33, 35, and 37, tip member 39, andlids 47, 49, and 51 may integrally be formed from silicone rubber, etc.

A bottom plate 59 (FIG. 3) is attached to the bottom of the base 11 ofthe actuator 1, thereby forming a space 61 through which the tubes 53are guided outside. The tubes 53 are collectively protected by aprotective tube 63.

The actuator 1 can carry out various operations, which will be explainedone by one.

FIGS. 6a to 7b shows a first operation of the actuator 1 for holding anobject M from four directions. In this operation, the flexible cylinders3, 5, 7, and 9 are operated in planes A, B, C, and D, respectively, thatare vertical to the plane of FIG. 2a and defined by a center axis 65 ofthe circle 21 on the base 11 and the center axes 3b, 5b, 7b, and 9b ofthe flexible cylinders, as shown in FIG. 2a.

To operate the flexible cylinders 3, 5, 7, and 9 in the respectiveplanes A, B, C, and D, the flexible cylinders are arranged such thatevery elastic partition wall 29 between the pressure chambers 302 and303 (502 and 503, 702 and 703,902 and 903) of the flexible cylinder 3(5, 7, 9) is oriented toward the center axis 65 in the plane A (B, C, C)as shown in FIGS. 6b and 7b. A pressurized fluid is supplied only to thepressure chambers 301, 501, 701, and 901 of the flexible cylinders asindicated with hatches in FIGS. 6b and 7b. Consequently, the flexiblecylinders curve inwardly in the respective planes A, B, C, and D.

In FIGS. 8a and 8b, the fluid is equally supplied to the pressurechambers 302, 303, 502, 503, 702, 703,902, and 903 of the flexiblecylinders to curve the flexible cylinders outwardly in the respectiveplanes A, B, C and D. In this case, an object M is held by the actuator1 from the inside as shown in FIG. 8a.

In this way, the elastic partition walls 29 of the flexible cylindersare positioned in the respective planes A, B, C, and D to easily achievethe first operation. This embodiment does not limit, however, theorientations of the elastic partition walls 29. namely, the elasticpartition walls 29 may be oriented in any directions to achieve thefirst operation because the flexible cylinders can curve in anydirection according to applied fluid pressures.

By controlling the actuator 1 in ways mentioned above, it can hold theobject M as shown in FIGS. 6a to 8b. Even if the object is made of glassand has a complicated shape as shown in FIG. 7a, the actuator 1 cancurve the flexible cylinders 3, 5, 7, and 9 according to the shape ofthe object to softly handle the object. The flexible cylinders can curveoutwardly as shown in FIG. 8a to hold the object from the inside. Theactuator 1 can vertically and horizontally move or turn the holdingobject only through the movements of the flexible cylinders withoutmoving an arm (not shown) to which the actuator 1 is attached. This isachieved by separately adjusting fluid pressure supplied to the flexiblecylinders, 3, 5, 7, and 9.

A second operation of the actuator 1 will be explained.

In this operation, the actuator 1 holds an object M from the front andrear sides or the left and right sides of the object as shown in FIG.9a. The actuator 1 is arranged in the same manner as in FIG. 6a, and theflexible cylinders 3, 5, 7, and 9 are operated in planes E and F, whichare vertical to the plane of FIG. 2a and defined by the center axes 3band 9b of the flexible cylinders 3 and 9 and the center axes 5b and 7bof the flexible cylinders 5 and 7.

In FIG. 9b, the pressure chambers 301, 501, 701, and 901 are filled witha fluid of high pressure, the pressure chambers 302, 503, 702, and 903with a fluid of low pressure, and the pressure chambers 303,502, 703,and 902 with no fluid. As a result, the flexible cylinders 3, 5, 7, and9 curve inwardly in the planes E and F.

Similar to the first operation, the second operation does not limit theorientations of the elastic partition walls 29 of the respectiveflexible cylinders.

For example, the elastic partition walls 29 may be positioned in theplanes E and F as shown in FIG. 9c. Namely, the elastic partition wall29 between the pressure chambers 302 and 303 of the flexible cylinder 3and that between the pressure chambers 902 and 903 of the flexiblecylinder 9 are oriented inwardly in the plane E, which the elasticpartition wall 29 between the pressure chambers 502 and 503 of theflexible cylinder 5 and that between the pressure chambers 702 and 703of the flexible cylinder 7 are inwardly oriented in the plane F.

When a pressurized fluid is supplied only to the pressure chambers 301,501, 701, and 901 of the flexible cylinders in FIG. 9c, the flexiblecylinders 3 and 9 curve inwardly in the plane E and the flexiblecylinders 5 and 7 inwardly in the plane F. On the other hand, when thefluid is equally supplied to the pressure chambers 302, 303,502, 503,702, 703, 902, and 903 of the flexible cylinders, the flexible cylinders3 and 9 curve outwardly in the plane E and the flexible cylinders 5 and7 outwardly in the plane F.

The flexible cylinders 3 and 9 may be separated far from the flexiblecylinders 5 and 7 to stably hold a long object.

A transferring operation of the actuator 1 will be explained withreference to FIGS. 10 to 13b. In this operation, the actuator 1 holdsand moves an object M.

In FIG. 10, the actuator 1 has the same arrangement as that of FIG. 9a.The flexible cylinders 3, 5, 7, and 9 of the actuator 1 hold an object Mfrom the front and rear sides or the left and right sides of the object.Under this state (FIG. 9c), the fluid is equally supplied further to thepressure chambers 301, 302, and 303 of the flexible cylinder 3, thepressure chambers 501,502, and 503 of the flexible cylinder 5, thepressure chambers 701, 702, and 703 of the flexible cylinder 7, and thepressure chambers 901, 902, and 903 of the flexible cylinder 9. As aresult, the flexible cylinders expand along the respective center axes3b, 5b, 7b, and 9b as shown in FIG. 11b to lift the object M as shown inFIG. 11a.

From the state of FIG. 11a, the fluid may be supplied to the pressurechambers 301 and 302 of the flexible cylinder 3, the pressure chambers501 and 502 of the flexible cylinder 5, the pressure chambers 701 and703 of the flexible cylinder 7, and the pressure chambers 901 and 903 ofthe flexible cylinder 9 as shown in FIG. 12b, thereby curving theflexible cylinders rightward and moving the object M rightward as shownin FIG. 12a.

Also, the fluid may be supplied in a way to expand the flexiblecylinders 5 and 7 while contracting or maintaining the flexiblecylinders 3 and 9 as they are as shown in FIG. 13b, thereby incliningthe object M as shown in FIG. 13a.

FIGS. 14 and 15 are views showing modifications of the second operation.In each case, an actuator 1 is provided with many flexible cylinders.

In FIG. 14, the actuator 1 has six flexible cylinders 3, 5, 7, 9, 67,and 69, which are pressurized as shown in the figure to hold an object Mbetween the cylinders 3, 5, and 67 and the cylinders 7, 9, and 69.

In FIG. 15, the actuator 1 has five flexible cylinders 3, 5, 7, 9, and67, among which the cylinders 3, 5, 7, and 9 are operated to hold anobject M.

A third operation of the actuator 1 will be explained.

In FIG. 16, an object M is pushed against the base portions of theflexible cylinders 3, 5, 7, and 9 or against the base 11 of the actuator1 from the front and rear sides or the left and right sides of theobject M.

As shown in FIG. 17, a pressurized fluid is supplied to the flexiblecylinders 3, 5, 7, and 9 to curve them inwardly in planes G, H, I, andJ, respectively, in a way to avoid their interference. The planes G, H,I, and J are orthogonal to the plane of FIG. 17. As a result, the objectM is pushed against the base portions of the flexible cylinders oragainst the base 11 of the actuator 1.

The flexible cylinders of the actuator 1 may be pressurized as shown inFIG. 18b to horizontally bend the cylinders, thereby turning the holdingobject M.

FIGS. 19 to 22 show the second, thirds, and fourth embodiments of thepresent invention.

In FIG. 19, center axes 3b and 5b of flexible cylinders 3 and 5 areinclined outwardly on a base 11 of an actuator 1. This arrangementallows the flexible cylinders 3 and 5 to have wide working ranges, afloating thing to be effectively protected, and its own robot arm to beguided to a holding object M.

In FIG. 20, center axes 3b and 5b of flexible cylinders 3 and 5 areinwardly inclined on a base 11 of an actuator 1. With this arrangement,top ends of the flexible cylinders 3 and 5 deeply bend toward a centeraxis 65 of the base 11, i.e., a center axis of a robot hand, so that anobject M may stably be held in the third operation explained withreference to FIG. 16.

In FIGS. 21 and 22, five flexible cylinders 3, 5, 7, 9, and 67 arearranged like a human hand. A base 71 comprises a base portion 71ahaving a fitting hole 73 for receiving the flexible cylinder 3corresponding to a thumb, and a base portion 71b having fitting holes75, 77, 79, and 81 for receiving the flexible cylinders 5, 7, 9, and 67corresponding to the remaining four fingers of the hand. The flexiblecylinders 3, 5, 7, 9, and 67 are inserted to the fitting holes 73, 75,77, 79, and 81, respectively, and adhered thereto. Tubes 53 of theflexible cylinders are passed through a space 61 inside the base portion71b, and collectively protected by a protective tube 63 on the outsideof the space 61. A back plate 83 closes the space 61. This actuator 1 iscontrolled to operate like a human hand.

FIGS. 23 to 25 show modifications of the flexible cylinder.

In FIG. 23, a tubular elastic body 23 is partly covered with a thin ring85, which is made of metal or plastics so that it may not easily deform.The thin ring 85 is adhered to a predetermined position on the tubularelastic body 23 to form a flexible cylinder 87. When a pressurized fluidis supplied to the flexible cylinder 87, the thin ring 85 does notdeform so that the flexible cylinder 87 may irregularly curve as shownin FIG. 24. The number, length, and fitting position of the thin rings85 are optional so that any curve suitable for an object may be realizedby the flexible cylinder 87.

In FIG. 25, part of an elastic tubular body 23 is formed of differentmaterial that does not easily deform. Namely, the elastic tubular body23 of a flexible cylinder 89 comprises parts 91 and 93 formed ofanisotropic material, and a part 95 formed of material that does noteasily deform compared with the material of the parts 91 and 93. Theseparts are separately formed, and fixedly connected to one another withadhesives, etc. This arrangement may provide nearly the same effect asthat of FIG. 23.

In the above embodiments, the peripheral wall of the elastic tubularbody of the flexible cylinder may be reinforced to form a smaller anglethan an angle of parallelism (at which the elastic tubular body does notradially expand or contract) with respect to a generating line of theflexible cylinder that is in parallel with the center axis of theflexible cylinder by winding the fiber at the smaller angle than theangle of parallelism, so that the flexible cylinder may contract axiallywith or without turning around the center axis when the fluid issupplied to the pressure chambers of the flexible cylinder.

The present invention is applicable not only for a robot hand but alsofor a transporting apparatus for transporting an object in a plane by anumber of closely arranged actuators.

In summary, an actuator of the present invention has a plurality offlexible cylinders fixed to a common base. The peripheral wall of eachflexible cylinder has anisotropic elasticity so that the flexiblecylinder may elastically deform, or curve while turning around an axialcenter thereof when pressurized fluids are supplied to pressure chambersof the flexible cylinder. As a result, the actuator can easily handle asoft or fragile object, or an object having many curved faces. Theflexible cylinders of the actuator can tilt or move to realize atransferring motion.

Various modifications will become possible for those skilled in the artafter receiving the teachings of the present disclosure withoutdeparting from the scope thereof.

What is claimed is:
 1. An actuator comprising:a base to which supportmembers are fastened; and at least two flexible cylinders, eachcomprising:a tubular elastic body having anisotropic elasticity; anelastic partition wall dividing the tubular elastic body into aplurality of individual pressure chambers; and a base portion made ofelastic material, the base portion having a thickness greater than thethickness of the tubular elastic body, the base portion designating anend of the flexible cylinder, the base portion being held by and betweenthe base and one of the support members, the flexible cylinders beingthereby supported in a predetermined positional relationship.
 2. Theactuator of claim 1, further comprising:pressure adjusting means forseparately adjusting the pressure in each of the pressure chambers ofeach of the flexible cylinders wherein the base portion is mounted in adepression in at least one of the base and a respective one of thesupport members, and wherein the base portion is adhesively-free heldfast by and between the base and the respective support member.
 3. Theactuator of claim 2, wherein the pressure adjusting means comprises:afluid source for supplying a fluid; valves for adjusting a pressure ofthe fluid supplied by the fluid source, the pressure adjusted fluidbeing supplied to a predetermined pressure chamber of the flexiblecylinders; and control means for controlling the valves.
 4. The actuatorof claim 1, wherein the flexible cylinders are arranged such that centeraxes thereof are parallel to each other.
 5. The actuator of claim 1,wherein the flexible cylinders are arranged equidistantly along a circleon the base.
 6. The actuator of claim 1, wherein the flexible cylindersare arranged such that the partition wall of each flexible cylinder isoriented toward a common axis perpendicular to a plane of the base. 7.The actuator of claim 1, wherein the flexible cylinders are arrangedsuch that at least one partition wall of a first flexible cylinder ispositioned in a plane common to at least one partition wall of a secondflexible cylinder adjacent said first flexible cylinder.
 8. The actuatorof claim 7, wherein the flexible cylinders are arranged such that atleast one partition wall of a third flexible cylinder is positioned inanother plane common to at least one partition wall of a fourth flexiblecylinder adjacent said third flexible cylinder, and wherein said planeand said another plane are parallel to each other.
 9. The actuator ofclaim 1, wherein center axes of the flexible cylinders are inclinedoutwardly on the base.
 10. The actuator of claim 1, wherein center axesof the flexible cylinders are inclined inwardly on the base.
 11. Theactuator of claim 1, wherein the flexible cylinders are arranged likefingers of a human hand.
 12. The actuator of claim 1, wherein each oneend of the pressure chambers is closed with a respective closing memberto which a round tip member is attached.
 13. An actuator comprising:abase to which support members are fastened; at least two flexiblecylinders, each comprising:a tubular elastic body having anisotropicelasticity; an elastic partition wall dividing the tubular elastic bodyinto a plurality of individual pressure chambers; and a base portionmade of elastic material, the base portion having a thickness greaterthan the thickness of the tubular elastic body, the base portiondesignating an end of the flexible cylinder, the base portion being heldby and between the base and one of the support members, the flexiblecylinders being thereby supported in a predetermined positionalrelationship; and pressure adjusting means for separately adjusting thepressure in each of the pressure chambers of each of the flexiblecylinders, the pressure adjusting means comprising: a fluid source forsupplying a fluid; valves for adjusting a pressure of the fluid suppliedby the fluid source, the pressure adjusted fluid being supplied to apredetermined pressure chamber of the flexible cylinders; and controlmeans for controlling the valves.
 14. The actuator of claim 13, whereinthe flexible cylinders are arranged such that center axes thereof areparallel to each otherwherein the base portion is mounted in adepression in at least one of the base and a respective one of thesupport members, and wherein the base portion is adhesively-free heldfast by and between the base and the respective support member.
 15. Theactuator of claim 13, wherein the flexible cylinders are arrangedequidistantly along a circle on the base.
 16. The actuator of claim 13,wherein the flexible cylinders are arranged such that the partition wallof each flexible cylinder is oriented toward a common axis perpendicularto a plane of the base.
 17. The actuator of claim 13, wherein theflexible cylinders are arranged such that at least one partition wall ofa first flexible cylinder is positioned in a plane common to at leastone partition wall of a second flexible cylinder adjacent said firstflexible cylinder.
 18. The actuator of claim 17, wherein the flexiblecylinders are arranged such that at least one partition wall of a thirdflexible cylinder is positioned in another plane common to at least onepartition wall of a fourth flexible cylinder adjacent said thirdflexible cylinder, and wherein said plane and said another plane areparallel to each other.
 19. The actuator of claim 13, wherein centeraxes of the flexible cylinders are inclined outwardly on the base. 20.The actuator of claim 13, wherein center axes of the flexible cylindersare inclined inwardly on the base.
 21. The actuator of claim 13, whereinthe flexible cylinders are arranged like fingers of a human hand. 22.The actuator of claim 13, wherein each one end of the pressure chambersis closed with a respective closing member to which a round tip memberis attached.